Earth boring drill



Dec. 5, 1933. L. c. BLACK EARTH BORING DRILL Filed Nov. 13, 1931 2Sheets-Sheet l INVENTOR. 1557-52 a 51 466 zzwzw A TTORNEYS.

Dec. 5, 1933; L. c. BLACK EARTH BORING DRILL Filed Nov. 13. 1931 2Sheets-Sheet 2 4 Patented Dec. 5, 1933 PATENT OFFICE EARTH BORING DRILLV Lester C. Black, Los Angeles, Calif.

Application November 13, 1931 Serial No. 574,749

3 Claims (01. 255-71) This invention relates generally to earth boringdrills of. the type utilizing rotary disc cutters, and to cutters "foruse with such drills.

It is an object of the invention to generally improve upon. the cuttingefiiciency of drills of the above type, both with respect to cuttingspeed and useful life; In this connection the invention is characterizedby a construction which will afiordboth a slicing or scraping action anda grinding action against the formation being drilled, and which willalso efiect positive rotation of the cutters abouttheir individual axes.

'It is a further object of the invention to devise arotary cutter of thedisc type, particularly adapted for application of hard tacingmaterials, such astungsten carbide, or stell-ite.

It is another object of the invention to devise a rotary disc cutter forearth boring drills which can .be readily manufactured as a steel orsteel alloy forging.

Further objects of the invention will appear from the followingdeseription,lin which the preferred embodiments of the invention havebeen set, forth in detail in conjunction with the .accompanyingdrawings. It :is understood that the appended claims are to be accordeda range of equivalents consistent with the state of the prior art. V

Referring to the. drawings: Figure 1 is a side elevational viewillustrating .an earth boring drill incorporating the present invention.

Figure '2 is a cross-sectional view taken along the line 2- -2 of Figure1.

Figure 3 is a cross-sectional view taken'on the line 3-3 of Figure l.

. Figure 4 is a fragmentary cross-sectional detail view illustrating thecentral conical .formation contactingthe cutter.

Figure '5 is a side elevational view illustrating one-half of a rotarydisc cutter constructed in accordance with my invention, this view beingtaken looking toward the outer face of the cutter.

. Figure 76 is a quarter section taken along the line 6-6 of Figure 15..

Figure '7 is a side .elevational view similar to Figure15, but lookingtoward the inner face of the cutter.

Figure 8 is a cross-sectional detail illustrating a modified formofcutter tooth.

The drill illustrated in Figures 1 to 4 inclusive consists generally ofa shank l0, tothe lower end of which the rotary disccutters 11 .aresecured. The shank 10, as in usual practicaisconnected to the lower endof a 'drill stem which. is

cutters are in substantially upright planes as rotated from the surfaceof the well. The cutters 11 are shown operating upon a rock formation12. While the cutters can be variously secured to the shank, it isconvenient to utilize a construction such as shown and claimed in my soPatent No. 1,655,176. Thus, as illustrated in the drawings, the shank isprovided with laterally extending studs 13 adapted to cooperate withremovable filler blocks 14-. Filler blocks 14 are adapted to be held inplace by a single bolt 15. Studs 13, together with filler blocks 14,complete circular journals .for the cutters, and by removing bolt .14and filler blocks 13, the cutters can be removed for replacement. .Byreference to Figure 3 it will be noted that the axes of the two cutters:11 are offset .laterallyupon either side of the central axis ofrotation of the shank 10. Likewise it is desirable to have the axes ofthe cutters parallel, so that in normal operation the shown f Cutters 11can be identical in construction,

and can be 'best understood by reference to Figures-5 to 1 inclusive.The body of each cutter includes a web portion 21 formed integrally withan outer portion 22 of enlarged width, Upon the outer periphery ofportion 22 are formed two sets of teeth identified as 23 and 24. As willbe presently explained, teeth 23 perform a reaming operation, whileteeth 24 perform a grinding operation and also serve to efiEect positiverotation of the cutter upon rotation of the shank.

Teeth 23 are formed with cutting edges 26 which are substantiallylinear, and with faces 27 and 28 which are illustrated as substantiallyplanar. For reasons which will presently be apparent, faces 27 can .betermed fiadv-ancing faces, while -faces 28 can be termed trailing faceswith respect to the, formation being cut. Teeth 24 are likewise providedwith edges 29, and while these edges do not form suchcutting operationsas are effected by edges 26, they do dig into the terms.- tion to effectpositive turning of the cutter. For certain reasons, as for example tolend strength, to facilitate'manufactureand to lend simplicity, teeth 23and 24 are merged integrally together. This merging of the two sets ofteeth is along a plane passed through the largest diameter of thecutter, and which has been indicated in Figure 4 at 31. In explanationof the appended claims it'should be noted that plane 31 divides theperiphery of the cutter into two portions, teeth 24 being formed uponthat peripheral portion of greatest width, and teeth 23 upon theperipheral portion of lesser width. Referring 110 back to Figures 1 and3, that side or face 32 of the cutter which is positioned adjacent theshank 10, can be termed the inner face, this being the lower face asviewed in Figure 4, while the other side of the cutter can be termed theouter face, corresponding to the upper face 33 as viewed in Figure 4.Teeth 24 extend between plane 31 and the inner face, while teeth 23extend between plane 31 and the outer face. Teeth 24 are preferablytapered from plane 31 towards the inner cutter face, as is apparent fromFigures 6 and 7, and their edges 29 extend generally toward the axis ofrotation of the-cutter. In other words, edges 29 can be considered assubstantially coincident with the surface of an imaginary truncated conehaving an axis coincident with the axis of rotation of the cutter. I

Cutting edges 26 of teeth 23 have an inclination which is opposite tothe inclination of edges 29 of teeth 24. In other words,these cuttingedges 26 lie generallyin lines which when projected converge toward theaxis of rotation of the cutter, and can also be considered as lyingapproximately in the surface of an imaginated truncated cone having anaxis coincident with the cutter axis. Cutting edges 26 also form such anangle with respect to a plane normal to the cutter axis, that the ends34 of these cutting edges, adjacent the outer cutter face 33, areadvanced in the direction of normal rotation of the cutter, indicated byarrows in Figure 5. In other words, cutting edges 26 can be said to liegenerally in lines which converge toward but which do not intersect withthe axis of rotation of the cutter.

The cutter described above is preferably made of an integral piece ofsuitable base metal possessing sufiicient strength to withstand thesevere stresses to which it is subjected. It can be convenientlymanufactured as a forging since the character of the teeth makes itpossible to form them in forging diesQ Suitable steel alloys arepreferable, such as manganese steel. To render the cutter more resistanttoabrasion, the advancing faces 27 are shown provided with a layer 36 ofhard abrasion resisting metallic material, which can be extended over atleast a portion of the adjacent faces of teeth 24. This layer or facingis preferably directly bonded to the base metal of the teeth as bywelding, and can be formed of materials like tungsten carbide orstellite. The facing is also preferably extended over all or a portionof the corresponding faces of teeth 24, shown in Figure 4.

Before explaining the mode of operation of my cutter, it can be pointedout that teeth 24 need not be continued as illustrated in Figures 3 to 5inclusive, but can be provided with slots 37 as illustrated in-Figure 6.Such a construction serves in effect to assist digging of teeth 24 intothe formation being cut, thus assuring more positive rotation of thecutter.

Referring now to Figures 1 to 4 for an'explanation of the mode ofoperation, it will'be assumed that shank 1G is rotated in a clockwisedirection as viewed in Figure 3. Because of the offset character of thecutter with respect to the vertical axis of the shank, only a portion ofeach cutter bears upon the formation being cut. The cutting edges 26 ofteeth 23are at such an angle that they are substantially coincident withthe surface of the formation being drilled, when in contact with thesame, as appears in Figure 3. The positioning of the cutters upon theshank affords a central formation cone 39, with which the teeth 24engage. Engagement of teeth 24 with the sides of cone 39 causesrelatively slow rotation of the cutters about their individual axes uponrotation of the drill shank. As the drill proceeds downwardly, the sidesof cone 39 are gradually ground and broken away. Referring to Figure 2,and assuming a clockwise rotation of the shank 10, individual rotationof the left hand cutter is in a counter-clockwise direction as viewedtoward its outer face, and individual rotation of the other cutter is ina similar direction when likewise viewed. The action of teeth 23 uponthe formation can be described as being both a slicing or a scrapingaction and a grinding action. This is by virtue of the fact that theends 34 of cutting edges 36 are advanced a certain amount with respectto the direction of rotation of each cutter. At the same time thisangularity of the cutting edges 26 tends to apply the advancing faces 27more directly against the formation. This makes it possible to applyhard facing materials like tungsten carbide to advancing faces 27, andwith my construction a facing of this character will not r adily breakor chip away, In addition to aiding in the cutting action, and in makingmore practical the application of hard material such as tungstencarbide, the setting of cutting edges 26, instead of retardingindividual rotation of the cutters, actually tends to assist suchrotation, so that in conjunction with teeth 24 the cutters arepositively rotated about their individual axes at all times. Theformation of cone 39 during normal drilling operations not only assistsin securing proper rotation of the cutters about their individual axes,but also materially assists in drilling a straight hole, as it functionsas a guide for the cutters.

I claim:

1. In an earth boring drill, a shank adapted to rotate about an axis, adisc type cutter rotatably secured to said shank, the axis of rotationof the cutter being transverse with respect to the axis of rotation ofthe shank and offset laterally therefrom, said cutter having teethformed about its.

periphery, said teeth being so arranged that their outer cutting edgeslie substantially in the frusto conical surface of either of oppositelyfaced truncated cones having axes coinciding with the 'axis of rotationof the cutter, thereby enabling teethv nearerthe outer face of thecutter to perform a reaming operation, and teeth nearer the inner faceto effect rotation of the cutter about its axis upon rotation of theshank, said teeth nearer the inner face of the cutter having cuttingedges extending generally along lines. which converge toward the axis ofrotation of the cutter, the cutting edges of the teeth nearer the outerface of the cutter lying in non-radial planes with their inner endsadvanced in the direction of rotation of the cutter about its axis.

2. In an earth boring drill, a shank adapted to rotate about an axis, adisc type cutter rotatably secured to said shank, the axis of rotationof the cutter being transverse with respect to the axis of rotation ofth shank and offset laterally therefrom, said cutter having teeth formedabout its periphery, said teeth being so arranged that their outercutting edges lie substantially in the frusto conical surface of eitherof oppositely faced truncated cones having axes coinciding with the axisof rotation of the cutter, thereby enabling teeth nearer the outer faceof the cutter to perform a reaming operation, and teeth nearer the innerface to effect rotation of the cutter about its axis upon rotation ofthe shank, the said cutting edges of the teethnearer the outer face ofthe cutter lying in non-radial planes with their inner ends advanced inthe direction of rotation of the cutter about its axis.

3. In an earth boring drill, a shank adapted to rotate about an axis, apair of disc-type cutters rotatably secured to said shank, said cuttersbeing spaced upon opposite sides of the axis of rotation of the shank,and the axis of rotation of each cutter being transverse with respect tothe axis of rotation of the shank and offset laterally therefrom, eachof said cutters having teeth formed about its periphery, said teethbeing so arranged that their outer cutting edges lie substantially inthe frusto conical surface of either of oppositely faced truncated coneshaving axes coinciding with the axis of rotation of the cutter, therebyenabling teeth nearer the outer face of each cutter to perform a reamingoperation, and teeth near the inner face of each cutter to effectrotation of the cutter about its axis upon rotation of the shank, thecutting edges of the teeth of each of said cutters nearer the outer faceof the same lying in non-radial planes with'their inner ends advanced inthe direction of rotation of the cutter about its axis.

LESTER 0. BLACK.

